We studied at necropsy 168 opiate addicts whose hearts were submitted for study with prime focus on modes of death and types of cardiac abnormalities. In the 168 patients, 20 various modes of death were identified; active infective endocarditis or its consequences in 67 (40%); drug overdose in 39 (24%), coronary artery disease in 14 (8%), pulmonary granulomatosis in 7 (4%), and 15 various diseases (7 cardiac and 8 non-cardiac) in the remaining 41 (24%) patients. Of the 168 hearts examined, only 7 (4%) were normal. Although infective endocarditis (active, healed or both) was most common [80 (48%) patients], there were a broad range of other cardiac abnormalities present: cardiomegaly in 114 (68%) (including 22 patients without another cardiac abnormality), coronary artery disease in 35 (21%), acquired valvular heart disease in 16 (10%), myocardial heart disease in 14 (8%), and congenital cardiac anomaly in 19 (11%). Of the 35 hearts with various coronary artery disease, 28 had significant (>75%) narrowing of the cross-sectional area of 1 or more of the 4 major (left main, left anterior descending, left circumflex, and right) epicardial coronary arteries by atherosclerotic plaque. Of 112 coronary arteries in these 28 hearts, 52 (46%) were significantly narrowed (a mean of 1.9 of the 4 major coronary arteries per patient). In 27 of these 28 cases, each 5-mm segment of the 4 major coronary arteries were examined histologically. Of the 1435 five-mm segments examined, 189 (13%) were narrowed 76 to 100% in cross-sectional area by plaque, 347 (24%), 51 to 75%; 336 (23%), 26 to 50%; and 563 segments (39%) were narrowed 0 to 25% in cross-sectional area by plaque.